Material characteristics of CLEARCERAM-Z 1.5m diameter mirror blanks for the TMT M1 segment blanksYoshihiko, Omata; Suzuki, Kaito; Kishi, Takayuki; Murozumi, Hisashi
doi: 10.1117/12.3019368pmid: N/A
Astronomy has a long history, and ancient civilizations established calendars based on observations of celestial bodies by eye. Humans continued to observe celestial bodies, but in the 17th century, a major breakthrough was made. This was the invention of the telescope. It made it possible to observe celestial bodies that could not be seen with the naked eye, and it became the foundation of modern science. Since then, astronomical telescopes have evolved from refracting telescopes, which use optical lenses, to reflecting telescopes, which use mirrors. The size and performance of the primary mirror is one of the most important factors in the observing capabilities of a reflecting telescope. The Thirty Meter Telescope (TMT), which is currently under construction, will have the world's largest primary mirror at 30 meters when completed, and is expected to make a significant contribution to the development of astronomy. Ohara supplies the zero-expansion material used for this primary mirror. In this paper, we present the results of measurements and inspections of the coefficient of thermal expansion (CTE), residual stress, bubbles, and foreign matter, etc., for the 357 1.5-meter-long blanks of Ohara CLEARCERAM-Z produced for the primary mirror of the TMT.
Maintaining the observatory: the role of facility condition assessments in astronomical facilitiesFalcon, Grecia A.; Adriaanse, David; Grigel, Eric J.; Maclean, John; Anticona, Piero
doi: 10.1117/12.3015086pmid: N/A
Astronomical observatories are pivotal in unraveling the mysteries of the cosmos. To ensure their operation and longevity, Facility Condition Assessments (FCAs) play a vital role in determining maintenance and funding needs for these unique facilities. By prioritizing maintenance needs, guiding and justifying budget allocation, and documenting compliance, FCAs assist in maintaining safety and operational efficiency, help sustain the scientific mission of these facilities, and help sustain their supporting infrastructure. This paper presents the general concept behind an FCA and a case study highlighting the impact of FCAs on several renowned astronomical facilities. As astronomy continues to expand our understanding of the universe, FCAs emerge as a critical tool in supporting the mission of these scientific institutions, fostering long-term sustainability, and justifying funding requirements to stakeholders.
Design and study of LAMOST reference fiber position measurement error compensation deviceZhou, Jinxin; Wang, Yingfu; Zhou, Jiahao; Liu, Ziming; Chen, Rongfeng; Xie, Jiacheng; Hu, Hongzhuan; Wang, Jianping; Liu, Zhigang; Chu, Jiaru; Zhou, Zengxiang
doi: 10.1117/12.3019668pmid: N/A
Accurate measurement of the position of the reference fiber is the key to ensure the positioning accuracy of the fiber, but due to the large aperture and large field of view of the LAMOST telescope, the diameter of its focal plate reaches 1.75m. The reference fiber is installed in the unit hole of the detection system as a reference. The reference fiber, which is the reference of the detection system, is installed in the unit hole of the focal plate, and the accurate detection of its position can only rely on the high-precision spatial measurement performance of the laser tracker. However, the systematic error of the laser tracker itself, as well as the temperature change and air flow in the environment have a large impact on the measurement results. This paper proposes a measurement error compensation device based on the relative position of spatial standard length rods, which consists of two or three indium steel rods with extremely small thermal expansion coefficients and accurately calibrated lengths as a reference, and the measurement deviations of the rod lengths and relative positions of the rods and the rods at the time of operation are related to the measurement errors of the reference fiber. According to the relevant algorithm, the position error of the reference fiber on the focal plane can be corrected in real time. Finally, experiments show that this device can effectively reduce the error of the laser tracker in the measurement of the position of the reference fiber.
The assembly, integration, and testing of the Extremely Large Telescope prefocal stationsLarringan, Asier; Murga, Gaizka; Ormaetxe, Amaia; Roldán, Manuel; Jolley, Paul; Lewis, Steffan
doi: 10.1117/12.3019725pmid: N/A
The Extremely Large Telescope (ELT) hosts two Prefocal Stations, one on each of its Nasmyth Platforms A and B. Both units will alternately distribute the light collected by the telescope’s giant optical system into the science instruments and other test equipment, deliver the focal surface images and pupil images of three natural guide stars for acquisition, guiding and wavefront sensing purposes and provide optical sensing to support phasing of the ELT primary mirrors, diagnostics, and maintenance of the optics as part of the Phasing and Diagnostics Station (supplied by ESO). As the subsystems were being assembled, the integration and verification activities proceeded gradually, following the typical V-process model approach. The full PFS Main System test without the M6 optics, which are being tested on their mirror mounts separately at the polisher premises, is now coming to its end and the overall system is ready for final testing.
Technical requirements flow-down for the concept design of the novel 50-meter Atacama Large Aperture Submm Telescope (AtLAST)Reichert, Matthias; Timpe, Martin; Kaercher, Hans; Mroczkowski, Tony; Groh, Manuel; Kiselev, Aleksej; Cicone, Claudia; Gallardo, Patricio; Puddu, Roberto; Klaasen, Pamela
doi: 10.1117/12.3018133pmid: N/A
The Atacama Large Aperture Submm Telescope (AtLAST) is a concept for a novel 50-meter class single-dish telescope operating at sub-millimeter and millimeter wavelengths (30-950 GHz). The telescope will provide an unprecedentedly wide field of view (FoV) of 1-2 degree diameter with a large receiver cabin housing six major instruments in Nasmyth and Cassegrain positions. The high observing frequencies, combined with the scanning operation movements with up to 3deg/second, place high demands on the accuracy and stability of the optical and structural components. The design features the introduction of a rocking chair type mount with an isostatically decoupled main reflector backup structure and an active main reflector surface with a high precision metrology system. The planned site location is in the Chilean Atacama Desert at approximately 5050 meters above sea level, near Llano de Chajnantor. This paper gives an overview of the optical, structural, and mechanical design concepts. It explains the flow-down from key science requirements to technical design decisions as well as showing design analogies from other existing large radio, (sub-)mm, and optical telescopes.
The Lowell Observatory Solar Telescope: a fiber feed into the Extreme Precision SpectrometerLlama, Joe; Zhao, Lily L.; Brewer, John M.; Szymkowiak, Andrew; Fischer, Debra A.; Collins, Michael; Tiegs, Jake; Cornelius, Frank
doi: 10.1117/12.3020494pmid: N/A
The signal induced by a temperate, terrestrial planet orbiting a Sun-like star is an order of magnitude smaller than the host stars’ intrinsic variability. Understanding stellar activity is, therefore, a fundamental obstacle in confirming the smallest exoplanets. We present the Lowell Observatory Solar Telescope (LOST), a solar feed for the EXtreme PREcision Spectrometer (EXPRES) at the 4.3-m Lowell Discovery Telescope (LDT). EXPRES is one of the newest high-resolution spectrographs that accurately measure extreme radial velocity. With LOST/EXPRES, we observe disk-integrated sunlight autonomously throughout the day. In clear conditions, we achieve a R ∼ 137, 500 optical spectrum of the Sun with a signal-to-noise of 500 in ∼ 150s. Data is reduced using the standard EXPRES pipeline with minimal modification to ensure the data are comparable to the observations of other stars with the LDT. During the first three years of operation, we find a daily RMS of 71cm/s. Additionally, having two EPRV spectrometers located in Arizona gives us an unprecedented opportunity to benchmark the performance of these planet-finders. We find a RMS of just 55cm/s when comparing data taken simultaneously with EXPRES and NEID.
Aerothermal support for TMT International Observatory enclosure and summit facilities subsystemsVogiatzis, Konstantinos; Thompson, Hugh; Trancho, Gelys
doi: 10.1117/12.3020282pmid: N/A
Computational Fluid Dynamics (CFD) and conjugate heat transfer models have been developed and/or updated to validate thermal requirements for the TMT International Observatory enclosure Heating, Ventilation and Air Conditioning (HVAC) system, azimuth and cap drive systems, interstitial space volume, as well as the Summit Facilities tunnel, mechanical room, utility room, and cooler exhaust. The resulting thermal environment is assessed and linked to performance, wherever applicable.
Panopticon: a telescope for our timesSaunders, Will; Chin, Timothy; Goodwin, Michael
doi: 10.1117/12.3023792pmid: N/A
We present a design for a wide-field spectroscopic telescope. The only large powered mirror is spherical, the resulting spherical aberration is corrected for each target separately, giving exceptional image quality. The telescope is a transit design, but still allows all-sky coverage. Three simultaneous modes are proposed: (a) natural seeing multi-object spectroscopy with 12m aperture over 3 FoV with ~25,000 targets; (b) multi-object AO with 12m aperture over 3 FoV with ~100 AO-corrected Integral Field Units each with 4” FoV; (c) ground layer AO-corrected integral field spectroscopy with 15m aperture and 13' FoV. Such a telescope would be uniquely powerful for large-area follow-up of imaging surveys; in each mode, the AOmega and survey speed exceed all existing facilities combined. The expected cost of this design is relatively modest, much closer to $500M than $1000M.